JPH0665714B2 - gasket - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket suitable as a gasket for an automobile engine or for other general industries, particularly for a cylinder head in an internal combustion engine such as an automobile engine.

2. Description of the Related Art Gaskets for cylinder heads in internal combustion engines such as automobile engines are used in contact with water or oil under high temperature and high pressure, and the problems that need to be solved. As a composition for use in a conventional cylinder head gasket, it is required to have excellent properties in various points such as stress relaxation, water resistance and oil resistance at high temperature and high pressure for a long period of time. Is not necessarily said to have sufficient performance for the above requirements.

Means for Solving the Problems In view of the above circumstances, the present inventors have conducted intensive research, and as a result, have developed the present invention.

In the present invention, the gasket body layer is composed of a composition comprising acrylonitrile-butadiene rubber and heat-resistant fiber, and a portion of the surface of the body layer or the entire surface thereof is in close contact with the surface of the body layer. An object of the present invention is to provide a gasket characterized by having a seal layer made of a non-oxirane-based UV-curable polyurethane acrylate.

The seal layer made of a non-oxirane-based UV-curable polyurethane acrylate is excellent in water resistance and oil resistance itself, and when the gasket body layer is composed of a composition containing acrylonitrile-butadiene rubber, The application of a UV-curable coating material during the formation of the seal layer, the UV-curing causes a strong bond between the seal layer and the acrylonitrile-butadiene rubber in the main body layer, resulting in a gasket excellent in various points such as water resistance and oil resistance. can get.

The main body layer in the present invention is basically composed of a composition consisting of an acrylonitrile-butadiene rubber and a heat resistant fiber described below, but if necessary, a filler, a coupling agent, a vulcanizing agent, a vulcanizing agent. Auxiliary agents, antioxidants, pigments, or other rubber chemicals may be added.

As the acrylonitrile-butadiene rubber, those conventionally used in the production of gaskets may be used, but especially those having an acrylonitrile content of 18 to 50% by weight (commercially available products of Nippon Zeon Co., Ltd., Nipol LX513, Bayer).
Perbunan 3810 manufactured by the company) is preferable.

As the heat-resistant fiber, a heat-resistant organic fiber, for example, an aromatic polyamide fiber (commercially available, Dupon't Kevlar, E
Examples include phenol resin fibers (such as Twaron manufactured by nko Co., Ltd., and commercially available products such as Kynol manufactured by Gunei Chemical Co., Ltd.), heat-resistant inorganic fibers such as asbestos, ceramic fibers, metal fibers, carbon fibers, and other fibers.
Examples of the ceramic fibers include natural or artificial non-metal inorganic solid material fibers such as rock wool, alumina silicate fiber, fused silica, silica glass fibers such as high silicate glass, alumina fiber, and zirconia fiber. It is illustrated. Examples of the metal fibers include fibers of heat resistant metals such as iron, copper and stainless steel. The heat-resistant fiber used in the present invention may be surface-treated with various resins or a coupling agent described later.

Among the above various heat resistant fibers, heat resistant organic fibers, particularly aromatic polyamide fibers and phenol resin fibers are preferable.

Apart from naturally occurring fibers such as asbestos, among the artificial heat resistant fibers used in the present invention, preferred ones are:
Outer diameter 50μm or less, especially 1-20μm, length 0.5-200
mm, especially 1 to 50 mm.

As the coupling agent, a silane coupling agent, a titanium coupling agent or another coupling agent is used.

The silane coupling agent is preferably γ-aminopropyltriethoxysilane (for example, manufactured by Shin-Etsu Chemical Co., Ltd.
KBE903), γ-mercaptopropyltrimethoxysilane (for example, KBM803 manufactured by Shin-Etsu Chemical Co., Ltd.), N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane (for example, KBM603 manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

The titanium coupling agent is preferably isopropyltriisostearoyl titanate (for example, TTS manufactured by Ajinomoto Co., Inc.).

Among various coupling agents, silane coupling agents are preferable, and among them, γ-aminopropyltriethoxysilane and γ-mercaptopropyltrimethoxysilane are particularly preferable.

Examples of the filler include talc, clay, barium sulfate, silica, mica, carbon, etc., or other
What is usually used for the gasket composition is used. The filler may be one whose surface has been previously treated with the above-mentioned coupling agent.

The amount of the heat-resistant fiber used is 100 parts by weight of acrylonitrile-butadiene rubber (hereinafter, when the rubber latex is used as the rubber, 100 parts by weight of the solid content contained in the latex). 50-500
It is used in parts by weight, preferably 75 to 300 parts by weight. The amount of the filler used is usually 300 to 1000 parts by weight, preferably 500 to 800 parts by weight, per 100 parts by weight of the acrylonitrile-butadiene rubber, except when almost no filler such as asbestos is used together. The amount of the coupling agent used is 0.5 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the rubber. The amount of the rubber chemicals used may be usual, but the total amount of the rubber chemicals mentioned above is preferably 3 to 20 parts by weight, and particularly preferably 5 to 10 parts by weight, per 100 parts by weight of the acrylonitrile-butadiene rubber. .

In the present invention, the seal layer provided on the gasket body layer is composed of ultraviolet ray-cured polyurethane acrylate. The seal layer can be formed by a method described later using an uncured, non-oxirane-based UV-curable coating material containing uncured polyurethane acrylate as a main component which does not contain an oxirane ring-containing compound as a component.

Examples of the uncured polyurethane acrylate containing no oxirane ring-containing compound include polyether oliol type polyurethane acrylate, polyester polyol type polyurethane acrylate, and polyurethane acrylate having an ether group and an ester group in the molecule. As the above polyether polyol,
For example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxy) Examples thereof include cyclohexyl) propane, bisphenol A to which ethylene oxide, propylene oxide and the like are added. Examples of the polyester polyol include reaction products of one or more of the above-mentioned polyether polyols with a dibasic acid such as adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, or an acid anhydride thereof. To be The diisocyanate used when producing a polyurethane acrylate using the above materials, tolylene diisocyanate, 4,4'-
Aromatic diisocyanates such as diphenylmethane diisocyanate, isoboron diisocyanate, alicyclic diisocyanates such as 4,4′-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, 2,
Aliphatic diisocyanates such as 2'-trimethylhexamethylene diisocyanate may be mentioned. Further, as the hydroxy group-containing polymerizable monomer, β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate, β-hydroxylauryl methacrylate, ε
-Hydroxy group-containing methacrylates such as caprolactone-β-hydroxyethyl methacrylate, etc. may be mentioned.

The non-oxirane-based UV-curable coating material used in the present invention, if necessary, various photopolymerization initiators such as acetophenone, benzophenone, Michler's ketone, benzyl, benzoin, benzoin ether, benzyl dimethyl ketal, photopolymerizable monomers, For example, monofunctional monomers such as methyl methacrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 1,3-butanediol diacrylate,
Bifunctional such as 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, polyethylene glycol-400 diacrylate, hydroxypipalinate neopentyl glycol diacrylate Monomers, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate,
It may contain a usual amount of trifunctional or polyfunctional monomers such as polymethylolpropane polyacrylate. Further, if necessary, an appropriate amount of a sensitizer, a stabilizer and the like may be mixed.

Examples of commercially available non-oxirane-based UV-curable polyurethane acrylate paints include ZF manufactured by Zeon Corporation.
Examples include -418-11, BYX-8017 manufactured by Asahi Denka Co., Ltd., and XNR-5470 manufactured by Nagase Plastics Co., Ltd.

The gasket of the present invention is applied from a gasket raw material sheet consisting only of the above-mentioned gasket main body layer constituent material, or a gasket raw material sheet obtained by sliding the above gasket main body layer constituent material on both sides of a core material such as an iron plate with hooks. The gasket is punched out in accordance with the target engine structure, and then the desired portion of the surface thereof, for example, the entire surface, only around water holes and oil holes, is screen-coated, roll-coated, curtain-coated with the above ultraviolet-curable paint. It can be easily manufactured by applying it with a method such as a dispenser and curing it with an ultraviolet ray by a usual method.

Embodiment FIG. 1 to FIG. 3 are partial sectional views of an embodiment of the present invention.

1 to 3, 1 is a gasket main body layer, 2
Is a core material made of an iron plate with a hook, and 3 is a seal layer made of the above-mentioned resin that is ultraviolet-cured. In the embodiment shown in FIG. 1, the gasket body layer 1 having no core material is provided with the seal layers 3 on both surfaces, and in the embodiment shown in FIG. 2, the gasket body layer 1 having the core material 2 is provided. The sealing layer 3 having a uniform thickness is provided on both surfaces excluding the perforated portions 4 such as water holes,
In the embodiment of FIG. 3, a gasket body layer 1 having a core material 2
The seal layer 3 is provided only around one surface of the perforated portion 4 such as the water hole.

Example 1 Acrylonitrile-butadiene rubber (Nipol LX51 manufactured by Nippon Zeon Co., Ltd.) having an acrylonitrile content of about 28% by weight.
3) 100 parts by weight, 700 parts by weight of asbestos, 100 parts by weight of talc filler (Talc SW manufactured by Nippon Talc Co., Ltd.), 5 parts by weight of vulcanizing agent (sulfur manufactured by Hosoi Chemical Co., Ltd.), vulcanization accelerator (Ouchi Shinko) 5 parts by weight of Nox Cellar TT manufactured by Kagaku Kogyo Co., Ltd. was rubbed on both sides of an iron plate with hook (thickness: 0.25 mm) and then heat vulcanized to obtain a gasket raw material sheet with a thickness of 1.20 mm. . Then, a doughnut-shaped sample having an outer diameter of 75 mm and an inner diameter of 55 mm was punched out from the sheet, and an ultraviolet curable polyurethane acrylate paint (manufactured by Nippon Zeon Co., Ltd.)
ZF418-11) is coated by the screen coating method and immediately irradiated with UV light for about 30 seconds to cure,
A seal layer having a height of 2 mm and a height of 0.1 mm was formed to obtain a gasket.

Example 2 As acrylonitrile-butadiene rubber, Perunan 3810 manufactured by Byer (content of acrylonitrile is about 38% by weight), and UV curable polyurethane acrylate paint XNR-5470 manufactured by Nagase Plastic Co., Ltd.
A gasket having the same structure was obtained by the same method as in Example 1 except that was used.

Example 3 Acrylonitrile-butadiene rubber (Nippol LX51 manufactured by Nippon Zeon Co., Ltd.) having an acrylonitrile content of about 28% by weight.
3) 100 parts by weight, aromatic polyamide fiber (Kevlar 29 manufactured by Dupon't) 40 parts by weight, rock wool (MF manufactured by Nippon Cement Co., Ltd.) 200 parts by weight, filler talc (Talc SW manufactured by Nippon Talc) 300 parts by weight, 350 parts by weight of soft clay (NeoCarrier K manufactured by Asada Milling Co., Ltd.), 5 parts by weight of vulcanizing agent (sulfur manufactured by Hosoi Chemical Co., Ltd.), vulcanization accelerator (NOX CELLER TT manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) ) A gasket having the same structure was obtained by the same method as in Example 1 except that the composition consisting of 5 parts by weight was used.

Example 4 A gasket having the same structure was obtained by the same method as in Example 1 except that an ultraviolet curable polyurethane acrylate paint (BYX-8017 manufactured by Asahi Denka Co., Ltd.) was used as the ultraviolet curable paint.

Comparative Example 1 A gasket having the same structure was obtained by the same method as in Example 1 except that an ultraviolet curable polyether acrylate was used as the ultraviolet curable coating material.

Comparative Example 2 A gasket having the same structure was obtained by the same method as in Example 1 except that an ultraviolet curable polyepoxy acrylate was used as the ultraviolet curable coating material.

Each of the gaskets obtained in Examples 1 to 6 and Comparative Examples 1 and 2 was subjected to the following water leak test and oil leak test, and the results are shown in the table below.

Water Leakage Test: Tighten the test gasket with pressure of 50kg / cm ² from both sides, increase the internal water pressure in steps of 0.5kg / cm ² to 0.5kg / cm ² , and keep it for 15 minutes at each rising water pressure to prevent water leakage. Check the generated internal water pressure. Visually check for water leaks.

Oil Leakage Test: A test different from the above water leakage test was performed only by using JIS No. 3 oil in place of water.

Example 5 The gasket obtained in Example 3 was mounted on a 4-cylinder engine (B631 manufactured by Mazda), and a cycle test was conducted at 20 ° C. and 130 ° C. for 5 minutes each. Even after 100 cycles, the initial sealing performance of 6.0 kg / cm ² or more of water sealing property and oil sealing property and 80 kg / cm ² or more of nitrogen gas sealing property was maintained. As is clear from Comparative Example 3 below, this performance cannot be achieved with a gasket provided with an ultraviolet-curable polysilicone sealing layer.

Comparative Example 3 A gasket having the same structure was obtained by the same method as in Example 3 except that an ultraviolet curable polysilicone (X-62-7397 manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the ultraviolet curable coating material, and the gasket was used in the above-mentioned Examples. When subjected to the same cycle test as 5
Water leakage at 1.0 kg / cm ² after 0 cycles, 3.0 kg / cm
Oil leakage at ^2, resulting in a nitrogen gas leakage at 10 kg / cm ^2.

In addition, the gasket having the ultraviolet-curable polysilicone sealing layer exhibits the performance of water leak occurrence water pressure of 8.0 kg / cm ² or more and oil leak occurrence hydraulic pressure of 20.0 kg / cm ² or more in the above-mentioned water leak test and oil leak test. In the initial stage of the engine mounting test, the sealing performance was equivalent to that of the gasket of Example 5 (Example 3).

Effect As described above, the gasket of the present invention is excellent in various points such as water resistance and oil resistance in the engine mounting test for a long period of time, and therefore, as a gasket for an automobile engine or other general industries, particularly an automobile engine. It is extremely useful for cylinder heads in internal combustion engines such as.

[Brief description of drawings]

1 to 3 are all partial sectional views of an embodiment of the present invention. 1 to 3, 1 is a gasket main body layer, 2
Is a core material made of an iron plate with a hook, 3 is a sealing layer made of an ultraviolet curable resin, and 4 is a perforated portion such as a water hole.

Continuation of the front page (56) Reference JP-A-60-129469 (JP, A) JP-A-49-65439 (JP, A) JP-A-59-159820 (JP, A)

Claims (2)

[Claims] 1. A gasket body layer is composed of a composition comprising acrylonitrile-butadiene rubber and heat-resistant fiber, and the surface of the body layer adheres to a part or the whole surface of the body layer. A gasket having a sealing layer made of the non-oxirane-based UV-curable polyurethane acrylate. 2. The heat-resistant fiber is an aromatic polyamide fiber and / or a phenolic resin fiber.
The gasket described in paragraph.